A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6650-01-391-2592
NSN 5895-01-383-8693
NSN 5990-00-470-2535
NSN 5998-00-102-4839
NSN 5895-01-494-4127
NSN 6220-00-957-8121
NSN 6135-01-210-8715
NSN 5975-01-125-1830
NSN 6145-01-385-0767
NSN 5910-01-613-0010
NSN 5835-00-223-7235
NSN 5998-00-234-0093